There are several considerations to account for in order to brew a cup of deliciously rich coffee. While an appropriate brewing temperature is among the critical aspects of brewing, water needs to be of high quality for pure, deep and rich coffee flavors. Some modern coffee makers come with in-built charcoal water filters. However, many coffee makers are still devoid of filters. Manufacturers seem to be unanimous: it’s important to use proper water to prevent damage to the coffee machine, and to yield the best tasting coffee. Owly Choice reader Alyssa recently reached out to us with the question…

Does my coffee maker purify water?

Owly Choice reader Alyssa

A question of whether a coffee maker purifies water or not is very fair, and I thank Alyssa for her inquiry.

There are 3 4 popular myths about purifying water in brewing coffee.

  1. Coffee makers filter water through boiling during the brewing. FALSE

  2. Since coffee makers reach boiling temperature, they are no ground for bacteria or fungi. FALSE

  3. The quality of water does not matter, since it’s all about quality of coffee. FALSE

  4. My coffee maker contains a charcoal water filter, so I am fine. RATHER FALSE


Alas, many coffee makers do not purify water

Though I want to believe otherwise, coffee makers typically do not purify water. Those that come with charcoal filters can only filter some elements, but most remain unfiltered. There are many reasons why coffee makers do not purify water.

↪ The vast majority of coffee makers do not reach boiling temperature. This includes some of the best drip coffee makers, best single serve coffee makers or best k-cup coffee makers. While it is true that boiling temperature can kill most of the bacteria, many coffee makers simply do not have the capacity to reach boiling temperature, and sustain it for an extended period of time. Even if they did, getting rid of chemicals found in water can be challenging.

↪ Even if a coffee maker could reach 212 F degrees, or boiling temperature, it would not be advisable to brew coffee in such hot water. As we explored the topic in the article on the proper temperature to brew coffee, anything above 205 F would burn coffee. The flavors would be acidic and mostly unpleasant.

↪ Bacteria can be killed if boiled for at least 3 minutes, as suggested by the Environmental Protection Agency. Though bacteria can be eradicated at or above 190 F degrees, this temperature would need to be kept up for at least 5 minutes. As EPA reports, it’s best to boil at 212 F degrees for 3 minutes. Unfortunately, electric coffee makers and kettles have automatic switch-offs as soon as water reaches certain temperature.

Why use purified water in coffee brewing?

This is a two fold question. First, why should we use purified water when brewing coffee? And, second, why should we NOT use tap water in coffee brewing?

  • Because coffee is 98.75% water, it should be of high quality. While this is true that oils, flavors and other solvents are extracted from coffee grounds, the vast majority of coffee beverage is water. The taste truly depends on it. We are all for getting high quality coffee grinds. However, they will not go far without contamination-free water.
  • Tap water can contain bacteria, fungi, mold and chemicals. It’s extremely difficult to get rid of unwanted particles found in most tap water.
  • Tap water can contain particles that will eventually damage a coffee maker, whether it is an espresso machine or a regular coffee maker. It is extremely important to descale and clean coffee makers regularly. When tap water is used, cleaning will need to become a routine. Manufacturers warn about this in the manuals.

How can I purify water for my coffee maker?

Coffee makers typically do not purify water. However, there are a couple of steps we can take to use high quality water:

  • Consider using bottled spring water or filtered water to have a clean coffee.

  • Consider thorough cleaning of your coffee maker equipment regularly. I personally clean my coffee maker once weekly, either with water or vinegar.  Some parts of coffee makers, such as gaskets or filter baskets, are particularly prone to mold and other bacteria due to the watery and warm environment.

  • Consider equipping your family with a reverse osmosis filters. Though those are more expensive, not only are they very effective, they tend to last for a long-time. Some examples include Home Master Reverse Osmosis filter, which can be installed under the sink.

Does my coffee maker purify water if it contains an in-built filter?

Yes, but mostly no. Some brands such as Cuisinart, Mr. Coffee, Keurig and others feature coffee makers that come with charcoal filters.

Given the structure of carbon-activated particles found in charcoal filters, we know that they can absorb some organic material. This material typically contributes to a peculiar flavor, odor or scent of the water, as reported by the EPA. However, charcoal filters do not effectively address heavy metals, bacteria and other microorganism found in the water.

Further, charcoal filters need to be replaced very frequently. They do have a short life span.

Bottom line

What water do you use in brewing your coffee? Do you use filtered or tap water? Does your coffee maker purify water? Let us know in the comments!

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